Modulating system for high-frequency currents



Sept. 9, 1930. w. RUNGE 1,775,213"

IODUMTIIIG SYSTBI FOR HIGH FREQUENCY CURIBIITS Filed m. 10, 1927 F MAMPUF/ER INVENTOR WLHEUA RUNGE TORNEY Patented Sept. 9, 1930 UTE WILHELM RUNGE, OF BERLIN, GERMANY, ASSIGNOR TO GESELLSCHAFT FUR DRAHT- LGSE TELEGEAPHIE Id. B. 331., OF BERLIN, GERMANY, A CORPORATIGIT OF GERMANY MODULATING SYSTEM FOB HIGH-FREQUENCY CUBRENTS Application. filed February 10, 1927, Serial No.

This invention relates to a modulating system for high frequency currents and more particularly to means whereby sound energy can be converted into electrical energy or potential variations. The invention provides an arrangement in which the change in the phase of an alternating current due to untuning is utilized for the purpose of insuring a higher sensitivity of the equipment. According to the invention, an alternating current, preferably an alternating current of high frequency, is supplied from a generator to a utilization circuit which is connected with said generator through a circuitbranch coupling so that the circuit in question consists of two branches. One of said branches contains a tuned system comprising a selfinductance coil and a condenser, while the other branch, for instance, may contain an ohmic resistance which is so dimensioned that both branches carry like currents, at the frequency of the supply. The tuned system in the first branch may conveniently consist of a series connection of a coil and a condenser.

With one of the elements of the tuned system, in other words, either with the condenser or else with the coil, there is connected a microphone or a telephone receiver in such a manner that, under the influence of the sound vibrations, untuning of said system and there by a variation in the current in the branch of the circuit is accomplished. N ow, with this circuit is connected or coupled a circuit in which electrical pulsations shall be produced as a function of the sound actions in such a manner that in the state of rest no electric energy will be transferred.

The novel features characteristic of my invention are set forth with particularity in the appended claims. The invention, itself, however, both as to its construction and mode of operation together with the objects and advantages thereof, will best be understood by reference to the following description taken in connection with the accompanying drawing in which the single figure shows an arrangement illustrative of my invention.

Referring to the drawing, it will be seen that alternating current from generator G is supplied to a circuit comprising two branches 167 3122, and in Germany February 23, 1926.

I and II. In branch I of this circuit is a condenser having capacitance C and a coil having self-inductance L and in addition a coil having self-inductance 1 The branch 11, apart from the coil 1, which is equal to coil 1,, has included. therein a resistance R which corresponds to the ohmic resistance of the series arrangement comprising condenser E, and coil L lVith said condenser C is connected a capacitive telephone or microphone M so that by virtue of the capacity variations of said microphone or telephone receiver, variations in tuning in branch I occur. In inductive coupling relationship -'ithc ils l and 1 is another coil L,, which, for instance, may form part of the input circuit III of an amplifier, as noted in the drawing. In the presence of equal coupling of the two branches, no potentials will be induced when the conditions are normal or balanced. But when the capacitance branch I undergoes variations on account of the fact that the microphone is spoken into, then a change in the current as regards its phase relations and its amplitude will be occasionedin branch And it will. be understood that this alteration will be proportionately more marked, the smaller the impedance of the inductance coil 1,, 1, used for the coupling.- By this variation in the current, electric energy will thus be transferred to the circuit 111 coupled with branches I and II. The arrangement herein described distinguishes itself by high sensitivity since, as pointed out, the change of the phase is utilized. Of course, also other forms of application of the basic idea are conceivable. For instance, the coupling of the two circuits need not be inductive in nature, in fact, it can be effected also in some other manner. Another point is that no capacitive (electrostatic) telephone or microphone is used which is, for instance, so connected with the self'inductance coil L that the value of the self-inductance of this coil is altered in dependence upon the speech vibrations with the result that untuning is produced in this manner.

Having thus described my invention, I claim:

1. An arrangement for modulating high frequency currents comprising a high' frequency source, a parallel branched circuit associated therewith, one branch of said circuit including a resistance, the other branch 5 including a seriesconnection of a condenser and an inductance, means associated with the condenser of the second branch for detuning the latter, and a circuit coupled to the parallel branched circuit.

2. An arrangement for modulating high frequency currents comprising a high frequency source, a parallel branched circuit associated therewith, one branch of said circuit including a resistance, the other branch including a series-connection of a condenser and an inductance, means associated with the condenser of the second branch fordet-uning the latter, each branch of said parallel branched circuit containing an equivalent inductance, and a utilization circuit inductively coupled to both of said equivalent inductances.-

3. An arrangement for modulating high frequency currents comprising a high frequency source, two branched circuits conductively associated therewith, one branch thereof comprising a tuned system, said other branch comprising'a resistance, each branch being so dimensioned that both carry like cur- 3g rents at the frequency of the source, a'utilization circuit coupled to said branched circuit, and means for detuning one branch of said first mentioned circuit. a

4. In an arrangement for modulating high frequency currents, a transformer, a circuit comprising a resistance the primary winding of said transformer, an inductance, and a capacity all in series, a high frequency source connected between the midpoint of said prian mary winding and a point of said circuit be tween said resistance and capacity, said source being connected so as to divide said circuit into two exactly electrically equivalent parts wherebyeach part of said circuit carries like currents at the frequency of the source, and

means for varying the capacity of said condenser in accordance with the desired modulations. I

WILHELM RUNGE. 

